Video color subcarrier frequency detection device and detection method
阅读说明：本技术 一种视频色副载波频率检出装置及检出方法 (Video color subcarrier frequency detection device and detection method ) 是由 陆国兵 吴刚 周国锋 于 2019-10-29 设计创作，主要内容包括：本发明公开了一种视频色副载波频率检出装置及检出方法,频率检出装置包括色副载波滤波器、放大器和单片机系统,色副载波滤波器的输出端与放大器的输入端连接,放大器的输出端与单片机系统的计数单元连接；待检测色副载波频率的视频信号通过色副载波滤波器进行滤波,滤波得到的载波经过放大器进行放大,放大得到的信号输入计数单元进行计数,单片机系统根据计数单元反馈的计数结果和计数时间得到计数频率,并根据计数频率与基准频率得到比例误差,进而根据允许比例误差阈值来判断视频信号的色副载波频率检出结果合不合格。本发明对测量到的信号直接计算误差ppm,并直接判断是否通过,不需要繁杂的计算和对操作人员的要求很低,减少了失误的可能。(The invention discloses a video color subcarrier frequency detection device and a detection method, wherein the frequency detection device comprises a color subcarrier filter, an amplifier and a singlechip system, the output end of the color subcarrier filter is connected with the input end of the amplifier, and the output end of the amplifier is connected with a counting unit of the singlechip system; the video signal of the to-be-detected color subcarrier frequency is filtered through a color subcarrier filter, a carrier obtained through filtering is amplified through an amplifier, the amplified signal is input into a counting unit to be counted, a single chip microcomputer system obtains the counting frequency according to the counting result and the counting time fed back by the counting unit, a proportional error is obtained according to the counting frequency and the reference frequency, and the detected result of the color subcarrier frequency of the video signal is judged to be unqualified according to an allowable proportional error threshold. The invention directly calculates the error ppm of the measured signal and directly judges whether the signal passes through, does not need complicated calculation and has low requirement on operators, and reduces the possibility of errors.)
1. A video color subcarrier frequency detection device is characterized by comprising a color subcarrier filter, an amplifier and a single chip microcomputer system, wherein the output end of the color subcarrier filter is connected with the input end of the amplifier, the output end of the amplifier is connected with a counting unit of the single chip microcomputer system, and the reference frequency error of the counting unit of the single chip microcomputer system is less than 1 ppm;
and the single chip microcomputer system obtains the counting frequency according to the counting result and the counting time fed back by the counting unit, obtains a proportional error according to the counting frequency and the reference frequency, and further judges whether the detection result of the color subcarrier frequency of the video signal is qualified or unqualified according to a preset allowable proportional error threshold value.
2. The video color subcarrier frequency detection apparatus according to claim 1, wherein the color subcarrier filter is a band pass filter having a bandwidth of-10 KHz to 10 KHz.
3. The video color subcarrier frequency detection apparatus according to claim 1, wherein the proportional error is calculated by the following equation:
4. The video color subcarrier frequency detection apparatus of claim 1, wherein an operating gain range of the amplifier is 20-50 dB.
5. The video color subcarrier frequency detection apparatus according to claim 1, wherein the count time is greater than or equal to 0.1 s.
6. The apparatus according to claim 1, wherein the detected result of the color subcarrier frequency of the video signal is determined to be acceptable if the absolute value of the proportional error is less than or equal to the preset allowable proportional error threshold, and is determined to be unacceptable otherwise.
7. The apparatus according to claim 1, further comprising a detection result display connected to an output of the single chip microcomputer system, wherein the detection result display is configured to display a scale error and/or a frequency detection result output by the single chip microcomputer system.
8. A video color subcarrier frequency detection method is characterized by comprising the following steps:
s1, filtering the video signal of the color subcarrier frequency to be detected;
s2, amplifying the carrier wave obtained by filtering in the step S1;
s3, counting the signals amplified in step S3 for a predetermined counting time;
s4, obtaining the counting frequency according to the counting result and the counting time in the step S3;
s5, obtaining a proportional error according to the counting frequency and the reference frequency, wherein the proportional error is calculated by using the following formula:
And S6, judging whether the absolute value of the proportional error is less than or equal to a preset allowable proportional error threshold value, if so, judging that the detection result of the color subcarrier frequency of the video signal is qualified, and otherwise, judging that the detection result is unqualified.
9. The video color subcarrier frequency detection method according to claim 8, characterized by being performed by the video color subcarrier frequency detection apparatus according to any one of claims 1 to 7.
10. The method for detecting the video color subcarrier frequency according to claim 8, further comprising, after step S5: sending the calculation result of the proportional error to a display device for displaying;
and/or
Further included after step S6 is: and sending the detection result of the color subcarrier frequency to a display device for displaying.
Technical Field
The invention relates to the field of color subcarrier frequency measurement, in particular to a video color subcarrier frequency detection device and a video color subcarrier frequency detection method.
Background
The device with composite video output usually has overlarge color subcarrier deviation in the production and manufacturing process, the video receiving device in the market has loose error, the deviation redundancy is very small, the image black and white phenomenon usually occurs when the deviation exceeds 100ppm, the display with high requirement is more required to be less than 10ppm, and for the requirement of color subcarrier frequency, the current national standard has no clear requirement, but the manufacturer usually faces practical problems in reality.
The measurement of the color subcarrier frequency has been conventionally measured using an expensive video analyzer, and no economical and practical instrument for measuring the color subcarrier frequency has been developed in the prior art.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a video color subcarrier frequency detection device and a detection method, which avoid complicated calculation, reduce the requirements on operators and reduce the frequency measurement error rate, and the technical scheme is as follows:
on one hand, the invention provides a video color subcarrier frequency detection device, which comprises a color subcarrier filter, an amplifier and a singlechip system, wherein the output end of the color subcarrier filter is connected with the input end of the amplifier, the output end of the amplifier is connected with a counting unit of the singlechip system, and the reference frequency error of the counting unit of the singlechip system is less than 1 ppm;
and the single chip microcomputer system obtains the counting frequency according to the counting result and the counting time fed back by the counting unit, obtains a proportional error according to the counting frequency and the reference frequency, and further judges whether the detection result of the color subcarrier frequency of the video signal is qualified or unqualified according to a preset allowable proportional error threshold value.
Preferably, the color subcarrier filter is a band-pass filter with a bandwidth of-10 KHz to 10 KHz.
Further, the proportional error is calculated by the following formula:
Preferably, the amplifier has an operating gain in the range of 20-50 dB.
Preferably, the counting time is greater than or equal to 0.1 s.
Further, if the absolute value of the proportional error is less than or equal to the preset allowable proportional error threshold, the detected result of the color subcarrier frequency of the video signal is determined to be qualified, otherwise, the detected result is determined to be unqualified.
Preferably, the video color subcarrier frequency detection device further comprises a detection result display connected with the output end of the single chip microcomputer system, and the detection result display is used for displaying the proportional error and/or the frequency detection result output by the single chip microcomputer system.
On the other hand, the invention also provides a video color subcarrier frequency detection method, which comprises the following steps:
s1, filtering the video signal of the color subcarrier frequency to be detected;
s2, amplifying the carrier wave obtained by filtering in the step S1;
s3, counting the signals amplified in step S3 for a predetermined counting time;
s4, obtaining the counting frequency according to the counting result and the counting time in the step S3;
s5, obtaining a proportional error according to the counting frequency and the reference frequency, wherein the proportional error is calculated by using the following formula:
And S6, judging whether the absolute value of the proportional error is less than or equal to a preset allowable proportional error threshold value, if so, judging that the detection result of the color subcarrier frequency of the video signal is qualified, and otherwise, judging that the detection result is unqualified.
Further, the video color subcarrier frequency detection method is implemented by using the video color subcarrier frequency detection device as described above.
Further, after step S5, the method further includes: sending the calculation result of the proportional error to a display device for displaying;
and/or
Further included after step S6 is: and sending the detection result of the color subcarrier frequency to a display device for displaying.
The technical scheme provided by the invention has the following beneficial effects:
a. the allowable proportion error threshold value can be flexibly set, and the method is suitable for the deviation redundancy of the video receiving equipment on the market to the error;
b. complex calculation is not needed, the requirement on operators is low, and the possibility of measurement errors is reduced.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a block diagram of a video subcarrier frequency detection apparatus according to an embodiment of the present invention;
fig. 2 is a flowchart of a method for detecting a video color subcarrier frequency according to an embodiment of the present invention.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, apparatus, article, or device that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or device.
In an embodiment of the present invention, a video subcarrier frequency detection apparatus is provided, as shown in fig. 1, the frequency detection apparatus includes a subcarrier filter, an amplifier, and a single chip microcomputer system, an output end of the subcarrier filter is connected to an input end of the amplifier, an output end of the amplifier is connected to a counting unit of the single chip microcomputer system, and a reference frequency error of the counting unit of the single chip microcomputer system is less than 1 ppm;
and the single chip microcomputer system obtains the counting frequency according to the counting result and the counting time fed back by the counting unit, obtains a proportional error according to the counting frequency and the reference frequency, and further judges whether the detection result of the color subcarrier frequency of the video signal is qualified or unqualified according to a preset allowable proportional error threshold value.
In one embodiment of the present invention, the counting time may be selected to be 0.1s, and then counting is performed within 0.1s, and for the case of higher accuracy requirement, 1s or longer may be selected.
In a preferred embodiment of the present invention, the color subcarrier filter is a band pass filter with a bandwidth of-10 KHz to 10KHz, and the operating gain range of the amplifier is 20-50dB, preferably 20-30 dB.
In the embodiment of the present invention, the proportional error is calculated by the following formula:
wherein, deltappmIs the proportional error, c _ num is the counting result, c _ time is the counting time, frefAs a reference frequency, the reference frequency fref＝4.43361875MHz。
And after the calculation result is obtained, if the absolute value of the proportional error is less than or equal to the preset allowable proportional error threshold, judging that the detection result of the color subcarrier frequency of the video signal is qualified, otherwise, judging that the detection result is unqualified.
In a preferred embodiment of the present invention, the video subcarrier frequency detection apparatus further includes a detection result display connected to an output terminal of the single chip microcomputer system, and the detection result display is configured to display a ratio error and/or a frequency detection result output by the single chip microcomputer system.
In an embodiment of the present invention, the present invention further provides a video color subcarrier frequency detection method, referring to fig. 2, the frequency detection method includes the following steps:
s1, filtering the video signal of the color subcarrier frequency to be detected;
s2, amplifying the carrier wave obtained by filtering in the step S1;
s3, counting the signals amplified in step S3 for a predetermined counting time;
s4, obtaining the counting frequency according to the counting result and the counting time in the step S3;
s5, obtaining a proportional error according to the counting frequency and the reference frequency, wherein the proportional error is calculated by using the following formula:
And S6, judging whether the absolute value of the proportional error is less than or equal to a preset allowable proportional error threshold value, if so, judging that the detection result of the color subcarrier frequency of the video signal is qualified, and otherwise, judging that the detection result is unqualified.
Preferably, the video color subcarrier frequency detection method is performed by using the video color subcarrier frequency detection apparatus as described above.
As shown in fig. 2, after step S5, the method further includes: sending the calculation result of the proportional error to a display device for displaying;
and/or
Further included after step S6 is: and sending the detection result of the color subcarrier frequency to a display device for displaying.
The frequency detection device of the invention directly calculates the error ppm of the measured signal, the error range can be flexibly set, and whether the signal passes or not is directly judged, the complicated calculation is not needed, the requirement on operators is low, and the possibility of error is reduced.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.